JP6611718B2 - Heat resistant composition for an electrically resistive and thermally conductive circuit breaker and load center and method for preparing the same - Google Patents

Description

  This application claims the benefit of US patent application Ser. No. 14 / 012,398, filed Apr. 28, 2013. This application is incorporated herein by reference.

  The concepts disclosed herein generally relate to electrical switchgear, and more particularly to circuit breakers and circuit breakers such as load panels or load centers. The concepts disclosed herein further relate to compositions for manufacturing electrical switchgear and related enclosures, and methods for preparing the compositions.

  The electrical switchgear includes, for example, a circuit switchgear and a circuit breaker. The circuit switching device and the circuit breaker are, for example, a circuit breaker, a contactor, a motor starter, a motor controller, and other load centers. These devices are well known in the art. For example, a circuit breaker includes at least a pair of separable contacts that are activated to protect an electrical circuit from damage due to an overcurrent condition, such as an overload condition or a relatively high level short circuit or fault condition. It is known to do. An electrical switchgear generally includes a housing that functions as a housing that houses electronic devices such as separable contacts, actuation mechanisms, and trip mechanisms therein, thereby providing strength and temperature insulation. Is granted. The materials for constructing the housing can be selected from a variety of known materials, and these materials are molded into a variety of shapes. Such a material is, for example, a liquid crystal polymer thermoplastic resin, but is not limited thereto. In some examples, the housing can be formed by a method known as insert molding. Insert molding is an injection molding method in which a synthetic resin is introduced (for example, injected) into a cavity or a mold and cured. As a result, a single molded plastic part (eg, a housing) is formed.

  Typically, molded plastics used in electrical switchgear devices such as circuit breakers or load centers are electrically resistive (i.e., no current flows) so that they are external to the device. Barriers are formed to shield and protect the positioned personnel from contact and electrical shock to electrically conductive components.

  Various techniques for producing nanoscale composite fibers are also well known in the art, such as electrospinning and force spinning techniques. In FIG. 1, a typical electrospinning method is shown. As shown in FIG. 1, the electrospinning apparatus includes a syringe 1, and the syringe 1 contains a polymer melt lump 2 or a solution. A spinning capillary 3 is disposed at the tip of the syringe 1, and the spinning capillary 3 is coupled to one pole of a voltage generation facility 6 (current source). The polymer molten mass 2 is conveyed from the syringe 1 to the spinning capillary 3 by the injection pump 9, and droplets are formed at the tip. The electric field between the spinning capillary 3 and the counter electrode 5 overcomes the surface tension of the polymer melt mass 2 or solution droplets exiting from the spinning capillary 3. As a result, the droplet coming out of the spinning capillary 3 is deformed, and when it reaches a critical potential, it is drawn out to form a thin filament (so-called jet). The charged jet is accelerated toward the counter electrode 5 in an electric field while continuously drawing a new polymer melt mass 2 or solution from the spinning capillary 3. The jet solidifies during the flight toward the counter electrode 5 by evaporation or cooling of the solvent. Thereby, continuous nanofibers 7 having a typical diameter of several nanometers to several micrometers are generated in a short time and bonded to each other. These nanofibers 7 are deposited on the template 4 associated with the counter electrode 5 in the form of a web or nonwoven mat. The conductive template 4 functions as a collector and is grounded together with the counter electrode 5. The polymer nanofibers 7 are spun directly on the conductive template 4.

  FIG. 2 shows a typical force spinning apparatus commercially available from FibreRio Technology Corporation. As shown in FIG. 2, the force spinning device includes a spinneret 20. The spinneret 20 has a storage portion 22 that stores the liquid material 24. During operation, the spinneret 20 is rotated centrifugally around the axis 25 at a high rotational speed per minute, generating hydrostatic and centrifugal forces. As the spinneret 20 rotates, hydrostatic and centrifugal forces press the liquid material 24 against the outer wall 26 where the orifice 27 is located. In FIG. 2, one orifice 27 is shown. However, the outer wall 26 may be formed with a plurality of orifices. The liquid material 24 enters and exits one or more orifices 27. Centrifugal force and hydrostatic force are combined to produce a jet of liquid material 24 that impinges on fiber collection section 28 and produces nanofibers 29. In FIG. 2, the fiber collecting unit 28 is disposed so as to surround only a part of the spinneret 20. However, the fiber collecting unit 28 may be disposed so as to surround the entire circumference of the spinneret 20.

  The electrostatic force used to create nanofibers in an electrospinning device has been replaced by centrifugal force in a force spinning device. The liquid material may include a molten material such as a solution or polymer melt. Examples of suitable materials include thermoplastic resins, thermosetting resins, ram extruded polymers such as polytetrafluoroethylene (PTFE). In addition to nanofibers, the device can also produce fibers in the micron and submicron range. In force spinning technology, conductivity and / or electrostatic charging is not a parameter related to the choice of material from which the fiber is made. Therefore, the range of materials for spinning can be expanded compared to electrospinning. For example, materials with low dielectric constants can be spun into nanofibers without the addition of salts or solvents. The control variables of the force spinning device are spinneret rotational speed, collection system design, and orifice shape and size.

  It is also well known in the art to produce injection molded parts by injecting a polymer material into a mold. In a typical injection molding process, heated molten plastic is pressed into a mold cavity under pressure. Injection molding includes a mold having a mold cavity. The mold cavity is formed in the shape of the desired finished part and is in direct fluid communication with the molten material source. The molten material is typically a resin, but may include a metal. The molten material is pushed into the mold cavity and cooled and cured. As a result, the molten material conforms to the shape of the mold cavity. The cooled part is then removed from the mold cavity. This process may be repeated to produce additional parts.

  In general, a mold cavity is a negative part that is manufactured. That is, when the mold cavity is filled with plastic and cooled, the plastic becomes a solid material and a finished positive part is obtained.

  The injection pressure can vary. The injection pressure may range from 34.475 MPa (5,000 psi) to 137.9 MPa (20,000 psi). With high pressure, it may be necessary to lock the mold closed during injection and cooling using a clamping force measured in tons.

  Conventional injection molding techniques can produce large quantities of parts with a high level of precision and consistency. For example, maintaining a tolerance of less than 0.0025 mm (0.001 inch) can be achieved relatively easily by an appropriate combination of materials, part design, and mold design. It has also been shown that, with further ingenuity, smaller (ie, tighter) tolerances can be achieved.

  Conventional methods for making electrical switchgears and enclosures such as circuit breakers use molding materials that are thermal insulators. In general, thermal insulation has low or minimal thermal conductivity and heat dissipation. Thereby, the circuit breaker and the housing manufactured from the thermal insulation electrically and thermally insulate the internal electronic device from the current flowing through the operating mechanism. As a result, the terminal or circuit breaker and other important parts of the housing may become hot. It is known in the art to measure and record these temperatures (at terminals or other critical points) to ensure safe operation and control of degradation or faults.

  Therefore, there is room for improvement in specifying the constituent material of the electrical switchgear to be molded. Used in the manufacture of electrical switchgears and enclosures, ultimately allowing these devices to dissipate heat, thereby reducing the amount of heat transferred and reducing the temperature at terminals or other critical points. There is a need for an electrically resistant and thermally conductive molding composition to reduce.

  In addition, there is room for improvement in the manufacture of injection molded parts, in particular in functionalizing the molded parts to impart selected properties.

  The above and other needs are met by embodiments of the concepts disclosed herein.

  In accordance with one aspect of the presently disclosed concept, a composition for manufacturing an electrically resistive and thermally conductive electrical switchgear is provided. The composition includes a first component that includes a polymer and a second component that includes nanofibers. The thermal conductivity of the second component is higher than the thermal conductivity of the first component, and an electrical switchgear comprising this composition is compared to an electrical switchgear composed of the first component without the second component. , Has improved heat dissipation.

The second component comprises a polymer, polymer-containing materials, metals, metal-containing materials, inorganic materials, and mixtures or we selected fiber material thereof, and a filler. The filler may have a thermal conductivity higher than that of the respective fiber material and the first component.

  In some embodiments, the first component and the second component may be combined to form a mixture. This mixture may be injection molded to form a molded body that forms at least a part of the electrical switchgear.

  In some other embodiments, the first component is injection molded to form a molded body that forms at least a portion of the electrical switchgear, and the second component is applied to at least a portion of the outer surface of the molded body. It may be deposited. The second component may be matte. The mat may be a porous body, and the molded body having the second component deposited on the outer surface may be transparent.

In accordance with another aspect of the concepts disclosed herein, a method is provided for preparing a molding composition for manufacturing an electrically resistive and thermally conductive electrical switchgear. The method includes obtaining a first component comprising a polymer and obtaining a second component comprising nanofibers. The second component comprises a polymer, polymer-containing materials, metals, metal-containing materials, inorganic materials, and mixtures or we selected fiber material thereof, and a filler. The thermal conductivity of the second component is higher than the thermal conductivity of the first component, and the electrical switchgear including this molding composition is compared with the electrical switchgear composed of the first component without the second component. And improved heat dissipation. The method further includes combining the first component and the second component in an injection molding process to form a molded part. The molded part at least partially constitutes an electrical switchgear.

  The second component may include a nanofiber layer at least partially deposited on the carrier substrate.

  In some embodiments, the step of combining the first component and the second component comprises at least partially depositing the second component on the inner surface of the mold, introducing the first component into the mold, and removing the first component. Curing, at least partially transferring the second component from the inner surface of the mold to the outer surface of the molded part, and removing the molded part from the mold. Alternatively, the second component may include nanofibers deposited directly on the inner surface of the mold without using a carrier film.

  In accordance with yet another aspect of the presently disclosed concept, a method is provided for reducing the internal temperature of an electrically resistive and thermally conductive electrical switchgear. The method includes providing a component of an electrical switchgear that includes combining a first component that includes a polymer and a second component that includes a nanofiber to form a mixture. The thermal conductivity of the second component is higher than the thermal conductivity of the first component, and the electrical switchgear including this mixture is compared with the electrical switchgear composed of the first component without the second component. , Has improved heat dissipation. The mixture is introduced into the mold and cured. The cured mixture is then removed from the mold to form a constituent material that is used to form at least a portion of the electrical switchgear.

  A full understanding of the concepts disclosed herein can be obtained by reading the following description of the preferred embodiments in conjunction with the accompanying drawings.

FIG. 1 is a diagram schematically showing a conventional electrospinning apparatus according to the prior art. FIG. 2 schematically shows a typical force spinning device according to the prior art. FIG. 3A schematically illustrates a process of depositing nanofibers in a mold and then on a molded part in accordance with some embodiments of the concepts disclosed herein. FIG. 3B schematically illustrates a process of depositing nanofibers in a mold and then on a molded part in accordance with some embodiments of the concepts disclosed herein. FIG. 3C schematically illustrates the process of depositing nanofibers in a mold and then on a molded part in accordance with some embodiments of the concepts disclosed herein.

  The term “load center” as used herein refers to any load panel, panel board, circuit breaker panel, or any surrounding or containing multiple circuit breakers for multiple branches or other load circuits. Means an appropriate housing. Further, as used herein, the term “electrical switchgear” is intended to include the associated housing or housing.

  In this specification, the statement that two or more parts are “connected” means that they are either directly coupled or coupled via one or more intermediate components. Further, in this specification, the statement that two or more parts are “attached” means that the parts are directly coupled.

  The concepts disclosed herein are described in the context of electrical switchgear such as circuit breakers and load centers and associated housings. However, it is clear that the concept disclosed herein can be applied to other types of electrical switchgear. Other types of electrical switchgear include, but are not limited to, other circuit switchgears and other circuit breakers such as contactors, motor starters, motor controllers, and other load controllers. It is not a thing.

  The concept disclosed herein includes, in some embodiments, an electrically resistive heat sink composition for manufacturing electrically resistive and thermally conductive electrical switchgear such as circuit breakers and housings. . It is well known in the art to construct an electrical switchgear from an electrically resistive material. Furthermore, it is well known in the art that electrical switchgear is constructed from a thermally insulating material such as a polymer (including but not limited to a liquid crystal polymer). Polymers are not very effective for heat dissipation because they are not highly thermally conductive. As a result, conventional electrical switchgear devices such as circuit breakers and enclosures formed from polymers retain heat, which results in high temperatures. Current actual operation may include measuring and recording the temperature in or around the circuit breaker to monitor and control the temperature rise.

  There are a variety of known materials suitable as heat transfer materials. However, these known materials are usually also electrically conductive. From the point of view of safety, the material used for manufacturing the electrical switchgear must have electrical insulation. Therefore, a material suitable for constructing an electrical switchgear cannot simply exhibit thermal conductivity without electrical resistance. Suitable materials for constructing the electrical switchgear are those that exhibit electrical resistance as well as thermal conductivity. An advantage of the concept disclosed herein is that, in order to produce an electrical switchgear that has both electrical resistance and thermal conductivity, the device can dissipate heat without becoming a conductor. it can

  In the concept disclosed herein, an electrically resistive and thermally conductive electrical switchgear is manufactured from a composition containing a first component comprising a polymer and a second component comprising nanofibers. Nanofibers exhibit higher thermal conductivity than polymer components. Therefore, the presence of the nanofiber component in the composition is effective for improving the thermal conductivity of an electrical switchgear formed from the composition. Thus, for example, in a circuit breaker formed from a composition of the disclosed concept, the presence of the nanofiber component increases heat dissipation by the circuit breaker, thereby causing the terminal or other location from the circuit breaker. Effective for reducing heat transfer to (usually where temperature rise needs to be monitored and controlled).

  In some embodiments, the conceptual composition disclosed herein improves the thermal conductivity of this region, lowers the internal temperature of the enclosure, and dissipates heat to the load center. Can be used to form The load center is typically composed of a metal such as steel. Therefore, although the temperature of the load center may increase as a result of heat transfer from the housing (for example, it may feel warm when touched), it is dissipated by the metal structure of the load center.

  The nanofibers of the composition are prepared using fiber materials and fillers. Fiber materials include polymers, polymer-containing materials, metals, metal-containing materials, inorganic materials such as ceramics, and mixtures thereof. Suitable fillers for use can be selected from a wide variety of known materials. In general, different fillers exhibit different properties and impart these different properties to the polymer component and composition and thus to an electrical switchgear constructed at least in part from the composition. The particular filler is selected based on the functionality of its material properties. Thus, properties or functionality are desirable for the resulting composition or molded part (eg, electrical switchgear). For example, thermally conductive fillers are used to prepare nanofibers that combine with the polymer component to impart thermal conductivity to the polymer component (not high thermal conductivity). Thereby, finally, thermal conductivity is imparted to the electrical switchgear formed therefrom. The filler (and resulting nanofiber component) exhibits a higher thermal conductivity than the polymer component, so that the thermal conductivity of the conceptual composition disclosed herein is that of the polymer component. Higher than that.

  The nanofiber component can be prepared using a variety of conventional techniques well known in the art. This prior art includes, but is not limited to, electrospinning and force spinning. The electrospinning method can be performed under conditions of environmental temperature and environmental pressure. Force spinning is typically performed under high temperature conditions, for example, at the melting temperature of the fiber material used to form the nanofibers.

  The polymer component includes polymers and / or polymer-containing materials (eg, matrix) and can be selected from these materials known for making electrical switchgear.

  In accordance with the concepts disclosed herein, the polymer component and the nanofiber component are combined to create an electrically resistive and thermally conductive electrical switchgear (eg, circuit breaker and housing) for electrical resistance. Forming a heat sink composition. A nanofiber component can be provided and then incorporated into the first polymer component. For example, the polymer component can be used to form a shaped body, such as an electrical switchgear or a portion thereof, using conventional injection molding methods. In general, for injection molding, a mold or mold cavity is selected, the mold or mold cavity is at least partially filled with a material (eg, a polymer) (eg, material is injected), and the mold or mold cavity is filled. Curing and removing the shaped body from the mold or mold cavity is included. The molded body can be formed under environmental temperature and environmental pressure conditions.

  In some embodiments, the nanofiber component is incorporated into the polymer component by at least partially embedding or depositing the nanofibers on the outer surface of the shaped body. As described above, the nanofiber component is prepared using conventional techniques in the art. For example, electrospinning or force spinning can be used to form deposited nanofibers on a substrate or collector. In another embodiment, a nanofiber layer can be formed at least partially on a collection, such as a carrier film, and then the collection having the nanofiber layer can be applied to a substrate. Alternatively, the nanofiber layer can be formed directly on the substrate (eg, directly on the inner surface of the mold) without using a carrier film. In embodiments where the nanofibers are formed on a carrier film, the carrier film is applied (eg, connected or attached) to the inner surface of the mold or mold cavity, and when the mold or mold cavity is filled, the polymer component is the film. Contact the top nanofiber. Then, when the molded polymer component is removed from the mold, the nanofibers are at least partially transferred from the surface of the film to the outer surface of the molded polymer component. At this time, the nanofibers are at least partially embedded (eg, injected) on the outer surface, or at least partially deposited on the outer surface (eg, coating the outer surface or laminating on the outer surface). Or laminating the outer surface) to form a molded part or molding composition comprising each of the polymer component and the nanofiber component.

  Alternatively, in embodiments where the nanofibers are formed directly on at least a portion of the inner surface of the mold, filling the mold or mold cavity causes the polymer component to contact the nanofibers on the inner surface of the mold or mold cavity and mold As the polymer component is removed from the mold, the nanofibers are at least partially transferred from the inner surface of the mold to the outer surface of the molded polymer component. At this time, the nanofibers are at least partially embedded (eg, injected) on the outer surface, or at least partially deposited on the outer surface (eg, coating the outer surface or laminating on the outer surface). Or laminating the outer surface) to form a molding composition comprising each of the polymer component and the nanofiber component.

  The nanofiber component may be in the form of a web (eg, non-woven) or mat. The web or mat may be highly porous. In embodiments where the polymer component is optically clear, deposition of the nanofiber component on the outer surface of the molded polymer component greatly reduces the optical clarity of the resulting molded composition. Never do.

  Various diameters of the nanofibers are possible. In some embodiments, the nanofiber diameter may be from about 10 nanometers to about 10 micrometers (microns). While not intending to be limited by theory, it is believed that the use of fibers having nanoscale dimensions improves the interaction and bonding between the nanofiber and polymer components. .

  In some embodiments, the conductivity of the surface of the molding composition comprising the polymer component and the nanofiber component is from about 10 ohms to about 100 megaohms. The conductivity of the surface of the molding composition can be controlled and adjusted by the particular filler selected and the particular amount of filler.

  FIG. 3 illustrates an apparatus and process for depositing a nanofiber coating on at least a portion of a surface of a molded part in accordance with some embodiments of the concepts disclosed herein. As shown in FIG. 3A, the step of placing a foil is used to disclose the process. The apparatus for this step includes a mold (die) 30, a carrier film 32, and conductive nanofibers 34. Conductive nanofibers 34 are deposited on carrier film 32 and layer there. A nozzle 36 having a nozzle head 38 is used to inject material 39 into the mold 30. Thus, the nozzle 36 includes a nozzle head 38 and material 39 contained therein. The material 39 may include a polymer or a polymer-containing material (for example, a resin material). FIG. 3B further illustrates an injection molding step in which the carrier film 32 containing conductive nanofibers 34 is in contact with (eg, attached to or applied to) the inner surface of the mold 30. The nozzle head 38 injects the material 39 into the mold 30. FIG. 3C illustrates the removal step, where the molded part 40 is manufactured, and the outer surface of the molded part 40 has conductive nanofibers 34 deposited in or on the outer surface. The conductive nanofibers 34 are at least partially transferred from the carrier film 32, and the carrier film 32 remains on the inner surface of the mold 30. Due to the presence of conductive nanofibers 34 on or in the surface of the molded part 40, the conductivity of the surface of the molded part 40 can be controlled or specified.

  Each of the polymer components and nanofiber components of the concepts disclosed herein may include additional additives or adjuvants. These additives and adjuvants are well known for use in preparing polymer-containing compositions and molded bodies.

  In some embodiments, at least a portion of the electrically resistive and thermally conductive electrical switchgear is disclosed herein by combining a polymer component, a nanofiber component, and optional additives to form a mixture. Formed from a conceptual composition. This mixture is injected or injected into a mold or mold cavity and cured for an appropriate amount of time to form a single molded part (eg, an electrical switchgear) that includes the incorporated polymer component and nanofiber component. .

  The conceptual composition disclosed herein functions as a heat sink in an electrically resistive electrical switchgear (eg, but not limited to a circuit breaker), housing, and load center.

  Although specific embodiments of the concepts disclosed herein have been described in detail, those skilled in the art will recognize that various modifications and changes can be made to these details in light of the overall teachings herein. Is understood. Accordingly, the specific configurations described herein are for illustrative purposes only and limit the scope of the concepts disclosed herein and any and all equivalents given the full scope of the appended claims. Not what you want.

Claims (8)

A molded part for producing an electrically resistive and thermally conductive electrical switchgear,
A molded body comprising a first component containing a polymer;
A nanofiber comprising a polymer or a fiber material comprising a polymer-containing material and a second component comprising a filler ,
The thermal conductivity of the second component is higher than the thermal conductivity of the first component, and the electrical switchgear including the molded part is compared with the electrical switchgear composed of the first component without the second component. Have improved heat dissipation,
The second component is or deposited embedded in at least a portion of the outer surface of the molded article comprising a first component is a web-shaped or mat-like, molded parts, characterized in that. The second component, further metals, metal-containing materials, inorganic materials, and fiber material selected from mixtures thereof or Ranaru groups, as well as in claim 1, characterized in that it comprises a thermally conductive filler The molded part as described. The molded part according to claim 2, wherein the thermal conductivity of the filler is higher than the thermal conductivity of the respective fiber material and the first component. The first component (39) is injection-molded to form a molded body (40) forming at least a part of the electrical switchgear, and the second component is formed on at least a part of the outer surface of the molded body (40). The molded part according to claim 1, wherein the molded part is deposited. A method for preparing a molding composition for producing an electrically resistive and thermally conductive electrical switchgear comprising:
Obtaining a first component comprising a polymer;
Obtaining a second component comprising nanofibers, and
The second component comprises a polymer, polymer-containing materials, metals, metal-containing materials, inorganic materials, and mixtures or we selected fiber material thereof, and the filler,
The thermal conductivity of the second component is higher than the thermal conductivity of the first component, and the electrical switchgear including the molding composition is compared with the electrical switchgear composed of the first component without the second component. With improved heat dissipation,
Further comprising combining a first component and a second component in an injection molding process to form a molded part (40);
The second component includes a nanofiber layer at least partially deposited on the carrier substrate (32);
The step of combining the first component and the second component is:
The carrier substrate (32) having the second component is brought into contact with the inner surface of the mold (30), the first component (39) is introduced into the mold (30), the first component (39) is cured, and the second component At least partially from the inner surface of the mold (30) to the outer surface of the molded part (40), and removing the molded part (40) from the mold (30) while the carrier substrate (32) remains in the mold. ,
A method, characterized in that the molded part (40) at least partially constitutes an electrical switchgear. The step of combining the first component and the second component is:
The second component is at least partially deposited on the inner surface of the mold (30), the first component (39) is introduced into the mold (30), the first component (39) is cured, and the second component is molded. The method of claim 5, comprising at least partially transferring from the inner surface of (30) to the outer surface of the molded part (40) and removing the molded part (40) from the mold (30).   The method of claim 6, wherein the second component comprises nanofibers deposited on a carrier film.   6. The electrically resistive and thermally conductive electrical switchgear is selected from the group consisting of a circuit breaker, a circuit breaker housing, a load center, and a load center housing. The method described.

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